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https://issues.apache.org/jira/browse/SPARK-12449?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=15087983#comment-15087983
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Yan commented on SPARK-12449:
-----------------------------

Stephan, 

By "partial op" I mean, for instance, partial map-side aggregation. There is 
also a Jira (SPARK-12686) that seems to echo this scenario as well.
Spark-10978 deals with predicate pushdown that used to get double evaluated, 
which is not related to the discussion of logical plan vs physical plan push 
down. 

> Pushing down arbitrary logical plans to data sources
> ----------------------------------------------------
>
>                 Key: SPARK-12449
>                 URL: https://issues.apache.org/jira/browse/SPARK-12449
>             Project: Spark
>          Issue Type: Improvement
>          Components: SQL
>            Reporter: Stephan Kessler
>         Attachments: pushingDownLogicalPlans.pdf
>
>
> With the help of the DataSource API we can pull data from external sources 
> for processing. Implementing interfaces such as {{PrunedFilteredScan}} allows 
> to push down filters and projects pruning unnecessary fields and rows 
> directly in the data source.
> However, data sources such as SQL Engines are capable of doing even more 
> preprocessing, e.g., evaluating aggregates. This is beneficial because it 
> would reduce the amount of data transferred from the source to Spark. The 
> existing interfaces do not allow such kind of processing in the source.
> We would propose to add a new interface {{CatalystSource}} that allows to 
> defer the processing of arbitrary logical plans to the data source. We have 
> already shown the details at the Spark Summit 2015 Europe 
> [https://spark-summit.org/eu-2015/events/the-pushdown-of-everything/]
> I will add a design document explaining details. 



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